Hurricane-induced nitrous oxide fluxes from a wet tropical forest

Hurricane activity is predicted to increase over the mid-Atlantic as global temperatures rise. Nitrous oxide (N(2)O), a greenhouse gas with a substantial source from tropical soils, may increase after hurricanes yet this effect has been insufficiently documented. On September 21, 1998, Hurricane Georges crossed Puerto Rico causing extensive defoliation. We used a before-after design to assess the effect of Georges on N(2)O emissions, and factors likely influencing N(2)O fluxes including soil inorganic nitrogen pools and soil water content in a humid tropical forest at El Verde, Puerto Rico. Emissions of N(2)O up to 7 months post-Georges ranged from 5.92 to 4.26 ng cm(-2) h(-1) and averaged five times greater than fluxes previously measured at the site. N(2)O emissions 27 months after the hurricane remained over two times greater than previously measured fluxes. Soil ammonium pools decreased after Georges and remained low. The first year after the hurricane, nitrate pools increased, but not significantly when compared against a single measurement made before the hurricane. Soil moisture and temperature did not differ significantly in the two sampling periods. These results suggest that hurricanes increase N(2)O fluxes in these forests by altering soil N transformations and the relative availabilities of inorganic nitrogen.